1. Field of the Invention
The present invention relates to a patterning method in nano-imprint lithography.
2. Description of the Related Art
In recent years, a problem in a photolithography step employed in a process of manufacturing a semiconductor device has become significant as semiconductor devices have become finer. That is, the current design rule of the state-of-the-art semiconductor device is as fine as several dozen nm half-pitch (hp); therefore, the conventional lithography by reduced pattern transfer using light does not provide sufficient resolution, and patterning is difficult to perform. To solve this problem, a nano-imprint technique has recently been proposed as an alternative to the lithography.
In the nano-imprint techniques disclosed, for example, in Japanese Patent Application Laid-open No. 2001-68411 and Japanese Patent Application Laid-open No. 2000-194142, an original mold (template) on which a pattern to be transferred is formed in advance is brought into contact with an organic material applied onto a substrate as a processing subject, and the organic material is cured by irradiating light, or by heating, thereby transferring the pattern on an organic material layer. In the nano-imprint technique, there are less variable factors such as focal depth, aberration, and an exposure amount, which have been a problem in the conventional lithography using light, and pattern transfer can be performed very simply, and accurately when a highly precise imprint mask is completed. That is, the nano-imprint technique is a patterning method that can form a very fine structure at low cost.
However, as has been explained, in the nano-imprint technique, a template and a processed substrate are brought into contact with each other, or brought close to each other to perform pattern transfer, and accordingly if, for example, irregularity, or a foreign matter such as particles is present on the surface of the processed substrate, a template may be chipped or cracked to be corrupted due to the irregularity, or the foreign matter. When the corrupted template is further used, patterns to be formed have common defects.
Japanese Patent Application Laid-open No. 2007-299994 discloses a technique about a machining device including a cleaning device for removing dusts adhered to a wafer surface. However, the technique has a problem that rapid pattern transfer cannot be performed due to the additional process of cleaning.